1sec pulse for defrost?

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=68115
Printed Date: September 09, 2025 at 9:25 PM

Topic: 1sec pulse for defrost?

Posted By: xttech
Subject: 1sec pulse for defrost?
Date Posted: December 11, 2005 at 12:12 AM

On my optional accessory harness off of the RS, I can setup Aux 3 (Trunk) to give a 1second pulse of 500 mA negative output. Can I hook this up to the back of my defrost button?

Replies:

Posted By: fingaz22
Date Posted: December 11, 2005 at 8:18 AM

check this post out we worked this one over and over for about 10 pages. https://www.the12volt.com/installbay/forum_posts.asp?tid=65562&KW=defrost

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JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs

Posted By: xttech
Date Posted: December 11, 2005 at 11:15 AM

Geeez,, I was hoping you wouldnt say that, heheh... I came across that in my searching and a majority of it, is over my head. I might be out in left field here, but I thought, where this wire can be set to a 1sec pulse that I could hook it up at the back of the switch, so it triggers the timed defrost switch and opens it up. Then when the timed portion is over, I just hit the Trunk button again to reset it.

I will re-read that post over and over again, to try to make some sense out of it.

thanks for the input though, appreciate the responses.

Posted By: fingaz22
Date Posted: December 11, 2005 at 12:48 PM

well there are a few different style defrost but most are commonly the same. witch oposes the problem of them being a mechanical switch for operation. and will take a little more then basic knoldge to accomplish. let us know what type of vechile you have and maybe we can try to get a solution for you.

-------------
JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs

Posted By: kohara73
Date Posted: December 11, 2005 at 1:57 PM

My car requires a ground to be supplied to the rear def. the entire time the RS is on. A pulse will only turn it on for the length of the pulse. This may be the case in alot of cars. The biggest variable will be whether you need to supply ground or +12V...and

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Keith

Posted By: fingaz22
Date Posted: December 11, 2005 at 2:11 PM

if that is the issue where you need a constant feed then you can get a relay setup for pulse to constant. that you will find in this forum in the relay section.that will give you a constant with one pulse and then when you pulse it again it will cut the constant feed off. and will be able to use neg. or pos.

what kind of car?

-------------
JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs

Posted By: xttech
Date Posted: December 11, 2005 at 8:10 PM

fingaz22

Its in my beater 85 Olds Firenza. I think its a mechanical defrost switch. To turn it on,its just a slight push forward and then light indicates its timed period on.....or it can be push downward and it will turn it off.

In the haynes manual, I cannot find any info on the defrost switch.

Posted By: fingaz22
Date Posted: December 11, 2005 at 8:25 PM

no actually if it dont click in it is not an mechanical switch. in your case you push it up and makes a contact then push it down and kills the contact. so that thread i posted mainly does not pertain to you.

my database is down right now and cant get a wiring diagram for this curcuit so can't help untill i have some schematics to work off of. you can pm tomorrow and i'll hopefully have it up. im sure someone on this site has done the type of curcuit you have and will be able to help.

have you taken it apart yet?can you take a pic like in the other thread i might be able to guide you better in this way. do you have knoldge of how eletrical curcuits work. if your totaly blind in this matter it will be harder to help. but will try my best.

Posted By: icarus_icarus
Date Posted: December 11, 2005 at 9:47 PM

The posts on my install were complicated becasue I had two defective modules posted_image

The diagram on page 4 that dualsport made is the best idea I would think if your defrost needs a 12V constant input.

Posted By: fingaz22
Date Posted: December 11, 2005 at 9:49 PM

here's another one that i just saw out the defrost. any info you can reseach on this subject can help. https://www.the12volt.com/installbay/forum_posts.asp?tid=65562&get=last

take a look and get back to me tomorrow with ant info you can provide and i'll take a look at them schematics when i can access them.

Posted By: xttech
Date Posted: December 11, 2005 at 10:01 PM

fingaz22 ....my bad, I meant to say, I dont think its mechanical.

I will take it apart tomorrow and get a pic if i can.Im pretty well blind with electrical wiring but i was able to install my RS, without having to pay an outrageous price,so I I am either guessing lucky or got a little idea. hehe I am good at searching and reading whatever i have to, in order to grasp what i need to.

I might be off the mark here, but if i push the defrost button and it is timed,wouldnt this be like a timed relay, and a pulse hitting it, would initially open it, then the built in timer takes over?

Someone told me, the stupid question is the one never asked. :-)

Posted By: fingaz22
Date Posted: December 12, 2005 at 8:58 PM

yes thats why i asked for some more info or better yet a pic so i can tell ya what wire or terminal will give it its pulse. im gonna try my database now. post that pic if you can

-------------
JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs

Posted By: xttech
Date Posted: December 12, 2005 at 10:06 PM

I never got around to it today. I forgot i had an appointment. I did notice when i turn on the defrost it sounds like it makes a click at the switch verses a separete timer relay i guess. Dunno if that is helpful.

Posted By: dualsport
Date Posted: December 12, 2005 at 11:16 PM

Sounds like a defrost switch timer similar to the one icarus was working with; when you push it on, it energizes the relay, which takes hold of the contact and holds it on. That would be the click you hear when you switch it on.

You can switch it off manually by forcing the contact away in the other direction, which opens the power going to the relay coil, so it stays off.

The problem that made it a bit more complicated was that the defroster relay wasn't designed to pull in by itself using electrical power alone, and needs to be helped along with a manual push- otherwise it could have just been supplied a brief pulse, and it would have latched on its own.

Posted By: fingaz22
Date Posted: December 13, 2005 at 7:32 PM

ya dual sport is right and it does sound like a mech. switch that icarus had. i didnt follow the rest of that post and don't know the out come but it was the thread that i first posted for you to look at. i'm sure if dual sport feels like he can help.

hey dual sport how did you guys make out on that? what was the out come?

Posted By: dualsport
Date Posted: December 13, 2005 at 10:05 PM

Well, it sorta hit a snag because Icarus's module had a bad "Ground Out While RS" signal, which we were planning to use for the relay control. I think he's looking into getting a different RS unit right now; the one he had seemed to have more than its fair share of failures out of the box.
So, it's still ongoing - posted_image